U.S. patent application number 14/110368 was filed with the patent office on 2014-04-24 for method for the manufacture of a fibre composite component, a reinforcement element and also a fibre composite component.
The applicant listed for this patent is Dirk Elbracht. Invention is credited to Dirk Elbracht.
Application Number | 20140113101 14/110368 |
Document ID | / |
Family ID | 46874954 |
Filed Date | 2014-04-24 |
United States Patent
Application |
20140113101 |
Kind Code |
A1 |
Elbracht; Dirk |
April 24, 2014 |
method for the manufacture of a fibre composite component, a
reinforcement element and also a fibre composite component
Abstract
A method for the manufacture of a fibre composite component with
a base element, and with at least one ancillary element bonded to
the base element. A reinforcement element is introduced in at least
one bonding region of the base element or the ancillary element for
purposes of developing a bonding surface for the ancillary element
or the base element. A reinforcement element with fibre sections,
the ends of which emanate from a bonding surface is provided. A
fibre composite component is provided with a base element, in the
bonding regions of which reinforcement elements are introduced, on
the bonding surfaces of which ancillary elements are bonded with
one such.
Inventors: |
Elbracht; Dirk; (Hamburg,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Elbracht; Dirk |
Hamburg |
|
DE |
|
|
Family ID: |
46874954 |
Appl. No.: |
14/110368 |
Filed: |
April 3, 2012 |
PCT Filed: |
April 3, 2012 |
PCT NO: |
PCT/EP2012/056084 |
371 Date: |
December 17, 2013 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61472640 |
Apr 7, 2011 |
|
|
|
Current U.S.
Class: |
428/86 ;
156/307.1; 428/85 |
Current CPC
Class: |
B29C 70/86 20130101;
B29C 70/24 20130101; B64C 1/12 20130101; Y02T 50/43 20130101; B29D
99/001 20130101; B29D 99/0014 20130101; Y10T 428/23914 20150401;
B29K 2105/246 20130101; B32B 5/12 20130101; B29L 2031/3085
20130101; B32B 7/04 20130101; Y02T 50/40 20130101; B29K 2105/24
20130101; B29L 2031/3082 20130101; B32B 38/10 20130101; B64C
2001/0072 20130101 |
Class at
Publication: |
428/86 ;
156/307.1; 428/85 |
International
Class: |
B32B 7/04 20060101
B32B007/04; B32B 5/12 20060101 B32B005/12 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 7, 2011 |
DE |
10 2011 006 977.1 |
Claims
1-12. (canceled)
13. A method for the manufacture of a fibre composite component,
with a base element, and with at least one ancillary element
connected to the base element, comprising the steps: preparing a
preform of the base element with at least one surface bonding
region, positioning a fibre composite component, with a bonding
surface for purposes of bonding the ancillary element in the
bonding region of the base element, integrating the reinforcement
element into the base element preform by the partial overlapping of
the reinforcement element with fibre layers of the base element
preform, curing the base element preform populated with the
reinforcement element, positioning a preform of the ancillary
element in the wet state on the base element on the bonding
surface, and curing the ancillary element preform.
14. The method in accordance with claim 13, wherein the at least
one reinforcement element is cured before positioning in the
bonding region.
15. The method in accordance with claim 13, wherein a preform of
the at least one reinforcement element is cured together with the
base element preform.
16. The method in accordance with claim 13, wherein the at least
one bonding surface is prepared by a removal of the surface of the
at least one reinforcement element, such that after the removal the
ends of fibre sections emanate from the at least one bonding
surface.
17. A reinforcement element for use in a method in accordance with
claim 13, for the manufacture of a fibre composite component, with
a multiplicity of fibre layers arranged in layers, with at least
one body section to be overlapped with fibre material of a base
element accommodating the reinforcement element, and with a bonding
surface for purposes of bonding an ancillary element, wherein the
ends of fibre sections emanate from the bonding surface.
18. The reinforcement element in accordance with claim 17, wherein
a multiplicity of body sections are provided in a star shape
surrounding the bonding surface, to be overlapped with fibre
material of a base element accommodating the reinforcement
element.
19. The reinforcement element in accordance with claim 17, wherein
at least some fibre layers have differing fibre orientations.
20. The reinforcement element in accordance with claim 17, wherein
some fibres are developed as continuous fibres with fibre sections
extending in the direction transverse to the fibre layers.
21. The reinforcement element in accordance with one of the claim
17, wherein for purposes of developing the bonding surface at least
one fibre layer is provided that is to be removed.
22. The reinforcement element in accordance with claim 21, wherein
at least one fibre layer that is to be removed is marked in each
case.
23. A fibre composite component manufactured in accordance with a
method in accordance with one of the claim 13, with a base element
with a multiplicity of bonding regions, a multiplicity of fibre
composite-type reinforcement elements arranged in the bonding
regions, each reinforcement element having a multiplicity of fibre
layers arranged in layers, with at least one body section to be
overlapped with fibre material of a base element accommodating the
reinforcement element, and with a bonding surface for purposes of
bonding an ancillary element, wherein the ends of fibre sections
emanate from the bonding surface, and with a multiplicity of
ancillary elements, which are connected to respective bonding
surface of the reinforcement elements.
24. The fibre composite component in accordance with claim 23,
wherein the fibre composite component is a stiffened shell
component of an aircraft with a skin field as the base element and
longitudinal stiffeners as the ancillary elements, wherein a
reinforcement element is integrated in each case into the skin
field in the region of run-outs of the longitudinal stiffeners.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of the U.S. Provisional
Application No. 61/472,640, filed on Apr. 7, 2011, and of the
German patent application No. 10 2011 006 977.1 filed on Apr. 7,
2011, the entire disclosures of which are incorporated herein by
way of reference.
BACKGROUND OF THE INVENTION
[0002] The invention concerns a method for the manufacture of a
fibre composite component, a reinforcement element for purposes of
developing a bonding surface, and also a fibre composite component
manufactured in accordance with such a method.
[0003] Shell components (e.g. fuselage and wing shells) of aircraft
are composed as a rule from a shell-type skin field and from
longitudinal stiffeners. The longitudinal stiffeners or ancillary
elements are extensively bonded to the skin field or base element,
and transport mainly axial loads. The skin field transports
primarily shear loads, wherein by means of the extensive bonding of
the longitudinal stiffeners the skin field is subdivided into a
multiplicity of small shear fields. In the case of fuselage shells
of a metallic form of construction the longitudinal stiffeners are
often riveted or welded to the skin field. In the case of fuselage
shells of a fibre composite form of construction, in a variant of
known art prefabricated longitudinal stiffeners are laid in as
cured elements during the manufacturing process of the skin field.
In an alternative variant of known art the longitudinal stiffeners
are adhesively bonded as wet elements onto the cured skin field.
For purposes of supporting the adhesively bonded joint, and/or in
the event of a separation of the adhesively bonded joint to prevent
a propagation of a delamination, the longitudinal stiffeners are,
at least in the region of their end run-outs, additionally riveted
to the skin field. Moreover the longitudinal stiffeners can be
riveted to the skin field in individual regions between their
run-outs, in order to improve the resistance of the skin field to
buckling. However, the rivets increase the assembly costs and the
weight of the fuselage shell. In particular the rivet holes must be
machined very precisely in order to prevent a weakening of the
fibrous material receiving the rivet holes. Moreover attention must
be paid to the material of the rivet, in order to prevent corrosion
in the event of contact of the rivets with, for example, carbon
fibres of the longitudinal stiffeners or the skin field.
SUMMARY OF THE INVENTION
[0004] The object of the invention is to create a method for the
manufacture of a fibre composite component, which enables an
improved adhesive bonded joint and/or bonding of at least one
ancillary element to a base element. Furthermore it is the object
of the invention to form a reinforcement element for purposes of
developing a bonding surface for the at least one ancillary
element, and also to create a fibre composite component that can be
subjected to high loads.
[0005] In an inventive method for the manufacture of at least one
fibre composite component with a base element and with at least one
ancillary element connected to the base element, a preform of the
base element is firstly prepared with at least one surface bonding
region. A fibre composite type of reinforcement element with a
bonding surface for purposes of bonding an ancillary element is
then positioned in the bonding region. After that the reinforcement
element is integrated into the base element preform by the partial
covering or overlapping of the reinforcement element with fibre
layers of the base element preform. The base element preform,
populated with the reinforcement element, is then cured. After that
a preform of the ancillary element in the wet state is positioned
on the base element on the bonding surface, and cured.
[0006] The integration of the bonding surface into a separate
reinforcement element enables an individual adjustment of the
bonding surface independently of the base element. The
reinforcement element can consist of separate materials and can
have fibre orientations that allow an optimal introduction of force
from the ancillary element into the base element and an optimal
materially bonded bonding of the ancillary element. Thereby, by the
covering or splicing in of the reinforcement element in some
sections, an extensive joint is created between the base element
and the reinforcement element. By means of the arrangement of the
ancillary element in the wet state on the bonding surface a
particularly intimate joint is created between the bonding surface
and the ancillary element, such that the ancillary element is
connected via the reinforcement element to the base element such
that it can accommodate high loads. Furthermore the inventive
method can be integrated into the existing production process for
the base element, without by this means increasing the number of
process steps.
[0007] In one example of embodiment the at least one reinforcement
element is cured before it is positioned in the bonding region. By
this means ease of manipulation and mounting of the reinforcement
element is possible.
[0008] In one preferred example of embodiment a preform of the at
least one reinforcement element is cured together with the base
element preform, as a result of which a joint is created between
the reinforcement element and the preform that is particularly able
to accommodate loads. For this purpose the reinforcement element
can consist of dry fibres, which are just connected with one
another by means of a thermoplastic binder.
[0009] The bonding surface is preferably prepared by a removal of
material from the surface of the at least one reinforcement element
such that after the removal of material fibres of the reinforcement
element emanate from the bonding surface. During the adhesive
bonding with the ancillary element the fibres emanating from the
bonding surface effect a mechanical anchorage across the adhesively
bonded layer, as a result of which an improvement of the strength
of the adhesively bonded joint is achieved, since this now takes a
mechanical form of a material bond quasi on the fibre plane. In
particular the damage tolerance of the adhesive joint is improved,
since a failure can only take place from fibre to fibre and thereby
much more energy is expended than is the case with a normal
adhesive joint. In a quasi-quantitative manner a new form of damage
behaviour is created, since any rapid propagation of damage is
prevented. The fibre sections can in principle run orthogonally and
also at an angle to the bonding surface, i.e. to the plane of the
joint. The fibre sections can also be spliced at their ends, or in
a similar manner to a Velcro fastening, can have a hooked or a
curved section. They preferably have a length such that they
securely bridge over the plane of the joint and can penetrate into
the ancillary element. The removal of materiel can take place by
means of a laser, by means of whose local introduction of heat
fibre layers of the reinforcement element located further below the
surface are not subjected to loading and the removal of material
can take place in a highly precise manner.
[0010] An inventive reinforcement element, for use in an inventive
method for the manufacture of a fibre composite component, has a
multiplicity of fibre layers, at least one body section to be
overlapped with fibre material of a base element, and a bonding
surface for purposes of bonding an ancillary element, wherein the
ends of fibre sections emanate from the bonding surface.
[0011] Such a reinforcement element allows an optimal bonding of
the ancillary element to the base element, since by means of the at
least one overlap a very harmonious integration of the
reinforcement element into the base element is possible, aligned
with the force distribution, and as a result of the fibre sections
protruding above the bonding surface, and thus above the plane of
the joint, a mechanical intermeshing can take place between the
reinforcement element and the ancillary element. The inventive
solution is therefore particularly suitable for an arrangement in
highly loaded regions such as in the case of run-outs of
longitudinal stiffeners in aircraft construction, and in regions in
which local effects such as buckling are conventionally to be
anticipated.
[0012] Moreover the propagation of delaminations is prevented in
the bonding region by means of the reinforcement element.
[0013] For the further optimisation of the integration of the
reinforcement element into the base element this can have a
multiplicity of body sections to be overlapped with fibre material
of the base element; these extend in a star shape from the bonding
surface.
[0014] For improvement of the load-bearing capacity of the
reinforcement element and/or for optimisation of the force
distribution at least some fibre layers can have differing fibre
orientations.
[0015] In particular it is preferred if some fibres of the
reinforcement element are developed as continuous fibres with fibre
sections extending in the direction transverse to the fibre layers
and/or in the thickness direction of the base element, since the
fibre sections, by the severing of their curved sections, which in
each case connect with one another, can easily be transferred into
the fibre sections whose ends are emanating from the bonding
surface.
[0016] The reinforcement element preferably has at least one fibre
layer to be removed in the region of the bonding surface. In
particular a plurality of fibre layers that are to be removed can
provide compensation for component and assembly tolerances. Just
one fibre layer represents an effective protection of the fibre
layer forming the respective bonding surface.
[0017] For the purpose of undertaking a visual check as to whether
the bonding surface is sufficiently prepared, the at least one
fibre layer that is to be removed can be marked. What is
conceivable, for example, is a colouring of the fibre layers that
are to be removed.
[0018] For the purpose of undertaking a visual check as to whether
the bonding surface is sufficiently prepared, a fibre layer that in
each case is to be removed can be marked.
[0019] An inventive fibre composite component has a base element
with a multiplicity of bonding regions, a multiplicity of fibre
composite-type reinforcement elements arranged in the bonding
regions, and a multiplicity of ancillary elements, which in each
case are bonded to a bonding surface of the reinforcement
elements.
[0020] Such a fibre composite component is distinguished by a
bonded joint that can be subjected to high loads and is
damage-tolerant, such that the conventional means of mechanical
attachment can be dispensed with to a considerable extent.
[0021] In one preferred example of embodiment the fibre composite
component is a stiffened shell component of an aircraft with a skin
field as the base element and longitudinal stiffeners as the
ancillary elements, wherein in the region of run-outs of the
longitudinal stiffeners a reinforcement element is in each case
integrated into the base element.
[0022] Other advantageous examples of embodiment of the invention
are the subject of further subsidiary claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In what follows a preferred example of embodiment of the
invention is elucidated in more detail with the aid of greatly
simplified schematic representations. Here:
[0024] FIG. 1 shows a perspective representation of an inventive
fibre composite component,
[0025] FIG. 2 shows individual elements of the fibre composite
component,
[0026] FIG. 3 shows a perspective representation of an inventive
reinforcement element,
[0027] FIG. 4 shows a detailed representation of the reinforcement
element,
[0028] FIG. 5 shows a perspective view of part of a prepared
bonding surface of the reinforcement element for purposes of
bonding an ancillary element.
[0029] FIG. 6 shows a section from a base element of the fibre
composite component with a bonding region for purposes of
accommodating the reinforcement element,
[0030] FIG. 7 shows a section through the fibre composite component
in the region of the at least one reinforcement element in the
region of its bonding surface, and
[0031] FIG. 8 shows a section through the fibre composite component
in the region of the at least one reinforcement element with a
developed bonding surface.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] FIG. 1 shows an inventive fibre composite component 1, with
a base element 2, to which a multiplicity of ancillary elements 4,
6 are connected. The fibre composite component 1 is, for example, a
shell component, in particular a fuselage shell of an aircraft
fuselage, with a skin field, which is stiffened by means of
longitudinal stiffeners or stringers, wherein the ancillary
elements 4, 6 represent the stringers, and the base element 2
represents the skin field.
[0033] The base element 2 is a shell-type fibre composite element
and consists preferably of a multiplicity of fibre webs, which in a
laying process such as ATL (Automatic Tape Laying) or FPL (Fibre
Placement Laying) have been laid down on a mould surface, not
shown, in a plurality of layers and orientations. The fibre webs
consist of carbon fibre mats arranged in a thermosetting or
thermoplastic resin matrix and are preferably so-called prepregs.
Alternatively, however, fibre mats of glass fibres, aramide fibres
and similar can also be used.
[0034] The ancillary elements 4, 6 have, for example, in each case
a T-shape cross-section with a foot section 8 and a web section 10
extending centrally from the foot section 8. They are developed in
each case as a fibre composite element with a plastic matrix and a
multiplicity of fibres arranged in the plastic matrix. The fibres
are preferably carbon fibres, glass fibres, aramide fibres and
similar. The plastic matrix preferably consists of a thermosetting
plastic. However, it can also have a thermoplastic base.
[0035] The ancillary elements 4, 6 with their respective foot
sections 8 are materially bonded to the base element 2 by means of
an adhesive joint forming the fibre composite component 1 with the
joining of the ancillary elements 4, 6 to the base element 2. For
this purpose they have, as shown in FIG. 2, a foot surface 12 in
each case extending across the foot section 8; the foot surface 12
is adhesively bonded with a section 14 of a surface 16 of the base
element 2. For purposes of improving the static and dynamic
strength of the adhesive joint as well as for purposes of improving
damage behaviour bonding surfaces 22, 24, represented in a hatched
manner and separately developed, are provided, at least in the
regions of the section 14 in which the ancillary elements 4, 6 with
their run-outs, i.e. with their end sections 18, 20 are arranged,
for purposes of bonding the ancillary elements 4, 6.
[0036] The bonding surfaces 22, 24 are in each case formed from a
separate reinforcement element 26, represented in FIG. 3, which is
integrally joined with the base element 2, i.e. is integrated into
the latter. The reinforcement element 26 is developed as a fibre
composite from a multiplicity of fibre layers/lays 28, 30, 32
arranged in layers (see FIG. 4), preferably with differing
orientations. The fibre layers 28, 30, 32 are preferably formed in
each case in the form of mats from a multiplicity of carbon fibres,
glass fibres, aramide fibres and similar. They are arranged
relative to one another such that the reinforcement element 26 has
an approximately trapezoidal longitudinal and transverse section
with wedge-type body sections 34, 36 that are facing away from one
another, which transition into one another at their edges, and
between whose wedge surfaces the bonding surface 22, 24 is
arranged. In the example of embodiment shown the reinforcement
element 26 has a greater extent in the longitudinal direction than
in the transverse direction, as a result of which the bonding
surface 22, 24 has a rectangular shape. However, the reinforcement
element 26 can also have other dimensional relationships. As
measured from a rectangular base surface 38, which in this example
of embodiment is facing away from the bonding surface 22, 24, the
bonding surface 22, 24 is arranged in the region of the
reinforcement element 26 in which the latter has its greatest
extent in the thickness direction.
[0037] As shown in FIG. 4, the reinforcement element 26 in the
region of the bonding surface 24, i.e. in the region of its
greatest thickness extent, in addition has a multiplicity of fibres
40, 42, 44 that are preferably embodied as continuous fibres. The
continuous fibres 40, 42, 44 have in each case a multiplicity of
fibre sections 46, 48 running in the thickness direction, i.e. the
direction transverse to the fibre layers 28, 30, 32; these fibre
sections 46, 48 are connected with one another via individual
curved sections 50. The curved sections 50 are positioned in the
region of the fibre layers 28, 30, which are removed during the
preparation of the bonding surface 22, 24 for adhesive bonding. For
purposes of identification of the fibre layers 28, 30 to be removed
they are marked in a colour, in contrast to the deeper-lying fibre
layers 32 in FIG. 4.
[0038] As shown in FIG. 5, after the preparation of the bonding
surface 22, 24, i.e.
[0039] after the removal of the fibre layers 28, 30 and after the
severing of the curved sections 50, the previously deeper-lying
fibre layer 32 forms the outer fibre layer. Moreover as a result of
the severing of the curved sections 50 the fibre sections 46, 48
individually protrude above the fibre layer 32 and thus their ends
protrude out of the bonding surface 22, 24.
[0040] As shown in FIG. 6 in a part section, the base element 2 for
purposes of accommodating the reinforcement elements 26 has a
multiplicity of bonding regions 52, whose respective individual
surfaces 54 correspond to the base surface 38 of the respective
reinforcement element 26.
[0041] In what follows preferred methods for the manufacture of the
fibre composite component are elucidated:
[0042] As shown in FIG. 7, to begin with a preform of the base
element 2 is developed by the laying down by layers of dry or
pre-impregnated fibre webs 55 on a mould surface. The bonding
regions 52 are then defined. Here the bonding regions 52 are in
each case provided in pairs such that the distance between the
bonding regions 26 of a pair corresponds in each case to the
distance between the end sections 18, 20 of the ancillary elements
4, 6, and such that the lateral distance between two pairs
corresponds in each case to a required distance between adjacent
ancillary elements 4, 6. After that the reinforcement elements 26
are positioned in the bonding regions 52, i.e. on their individual
surfaces 54. The reinforcement elements 26 can be developed in the
cured state, or as dry preforms that have simply been wetted with a
binder. After the positioning of the reinforcement elements 26 the
other layers of the base element preform are laid down, wherein for
purposes of integration of the reinforcement elements 26 individual
fibre webs 56, 58 of the base element preform are laid over the
wedge-type body sections 34, 36 of the reinforcement elements 26.
After all the layers have been laid down the base element preform,
populated with the reinforcement elements 26, is cured and
consolidated to become the base element 2. If the reinforcement
elements 26 have been positioned in the bonding regions 26 as dry
preforms, these are also impregnated and consolidated during the
process of curing the base element preform, such that the fibres of
the reinforcement elements 26 and the fibres of the base element 2
are accommodated in a common resin matrix. After the integration of
the reinforcement elements 26 into the bonding regions 52, i.e.
after the laying down of the fibre webs 56, 58, the reinforcement
elements 24 in the region of the bonding surfaces 22, 24 protrude
above the surrounding surface sections of the base element 2 by the
number of fibre layers 28, 30 that are removed during the
development of the bonding surfaces 22, 24.
[0043] After the consolidation of the base element 2 populated with
the reinforcement elements 26, the bonding surfaces 22, 24 of the
reinforcement elements 26, as shown in FIG. 8, are prepared for the
bonding of the ancillary elements 4, 6. Here the reinforcement
elements 26 in the region of the bonding surfaces 22, 24 are
quasi-levelled such that the prepared bonding surfaces 22, 24
transition into the surrounding surface sections in a stepless
manner, and with the outer fibre layers 56 form a plane and
continuous surface 16. For this purpose the fibre layers 28, 30
protruding above the surrounding surface sections are removed over
the surface area and the bond-side curved sections 50 of the fibre
sections 46, 48 running in the thickness direction are removed,
such that they are exposed and their ends emanate from the bonding
surface 22, 24 (see also FIG. 5). The preparation of the bonding
surfaces 22, 24 is preferably undertaken by means of
electromagnetic radiation such as laser radiation.
[0044] After the preparation of the bonding surfaces 22, 24 wet,
resin-impregnated preforms of the ancillary elements 4, 6 with
their end sections 18, 20 are positioned on the bonding surfaces
22, 24.
[0045] Finally the structure is forwarded to an autoclave process,
in which the resin matrix of the ancillary element preforms is
firstly fluidised, by the introduction of heat, and then cured.
Here the ends of the ancillary element preforms are pressed against
the bonding surfaces 22, 24, as a result of the pressure prevailing
in the autoclave, such that the freestanding fibre sections 46, 48
orientated at right angles to the plane of the joint are pressed
into the ancillary element preforms and thus provide a bridging
function over and above that of the adhesive bonded joint. After
the autoclave process the ancillary elements 4, 6 are thus not only
materially bonded with the base element 2, and with the
reinforcement elements 26, but in accordance with the invention are
also mechanically intermeshed with at least the reinforcement
elements 26 via the fibre sections 46, 48 emanating from the
bonding surface 22, 24 and protruding above the plane of the
joint.
[0046] Disclosed is a method for the manufacture of a fibre
composite component with a base element, and with at least one
ancillary element bonded to the base element, wherein a
reinforcement element is introduced in at least one bonding region
of the base element or the ancillary element for purposes of
developing a bonding surface for the ancillary element or the base
element, a reinforcement element with fibre sections, the ends of
which emanate from a bonding surface, also a fibre composite
component with a base element, in the bonding regions of which
reinforcement elements are introduced, on the bonding surfaces of
which ancillary elements are bonded with one such.
[0047] As is apparent from the foregoing specification, the
invention is susceptible of being embodied with various alterations
and modifications which may differ particularly from those that
have been described in the preceding specification and description.
It should be understood that I wish to embody within the scope of
the patent warranted hereon all such modifications as reasonably
and properly come within the scope of my contribution to the
art.
REFERENCE SYMBOL LIST
[0048] 1 Fibre composite component [0049] 2 Base element [0050] 4
Ancillary element [0051] 6 Ancillary element [0052] 8 Foot section
[0053] 10 Web section [0054] 12 Foot surface [0055] 14 Surface
section [0056] 16 Surface [0057] 18 End section [0058] 20 End
section [0059] 22 Bonding surface [0060] 24 Bonding surface [0061]
28 Fibre layer [0062] 30 Fibre layer [0063] 32 Fibre layer [0064]
34 Body section [0065] 36 Body section [0066] 38 Base surface
[0067] 40 Fibre [0068] 42 Fibre [0069] 44 Fibre [0070] 46 Fibre
section [0071] 48 Fibre section [0072] 50 Curved section [0073] 52
Bonding region [0074] 54 Individual surface [0075] 55 Fibre layer
[0076] 56 Fibre material [0077] 58 Fibre material
* * * * *